Automatic vehicle transmissions generally include a number of clutches that are selectively engaged by a transmission control system in order to select a gear ratio for the transmission. Often, the clutches are hydraulically controlled. In some examples, the components of a hydraulically controlled clutch include an electric solenoid driver, a clutch solenoid and the clutch itself. In order to control a clutch, the electric solenoid driver delivers an electrical signal to activate the clutch solenoid, which, in turn, controls hydraulic fluid pressure in order to control the clutch. In this manner, electrical control signals from the electric solenoid driver are used to engage and disengage hydraulically controlled clutches within an automatic transmission. By selectively engaging different clutches or combination of clutches within the automatic transmission, the transmission control system selects a gear ratio for the transmission.
To avoid damage to the gearing of an automatic transmission, it is important not to engage gears for more than one gear ratio of an automatic transmission at a time. For this reason, automatic transmission control programs generally include a short time delay between the disengagement of one gear ratio and the engagement of another gear ratio. Furthermore, the physical components of hydraulically controlled clutches may respond differently as they wear over time and/or in different environmental conditions, such as varying temperatures. For this reason, transmission control programs may attempt to account for these variations by adjusting control parameters to account for varying environmental conditions and/or transmission wear over time.